Effect of bremsstrahlung on buildup factors on deep γ-ray penetration

To investigate the effect of bremsstrahlung on the buildup factors of scattered gamma radiation conducted are calculations for a flat isotropic source with the energy E0=6,8,10 MeV in the iron, tin and lead media of the thicknesses up to 50 lengths of free pass. The calculations are made using Ssub(n)-method in S6P6-approximation with and without account of bremsstrahlung. It is found that 1) the contribution of bremsstrahlung to the buildup factor value of scattered radiation increases sharply with energy increase of γ-radiation and of the atomic number; 2) dependence of the contribution of bremsstrahlung on the shield thickness is characterized by maximum, position of which is shifted to the side of greater penetration depths with radiation energy increase